[PHP-NOTES] note 130416 added to class.xmlreader

Be aware that the property "attributeCount" doesn't count #FIXED marked DTD properties. Call the getAttribute method to get the default value.

```XML
# file.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE user [
    <!ELEMENT user (#PCDATA)>
    <!ATTLIST user
        race CDATA #FIXED "human">
]>
<user>John</user>
```

<?php
$reader = XMLReader::open('file.xml');

$reader->read(); // nodeType === XMLReader::DOC_TYPE
$reader->read(); // nodeType === XMLReader::ELEMENT
echo $reader->attributeCount, PHP_EOL; // 0
echo $reader->getAttribute('race'), PHP_EOL; // "human"
?>
----
Server IP: 45.112.84.4
Probable Submitter: 80.90.5.137 (proxied: 84.55.60.33)
----
Manual Page -- https://php.net/manual/en/class.xmlreader.php
Edit        -- https://main.php.net/note/edit/130416
Del: integrated  -- https://main.php.net/note/delete/130416/integrated
Del: useless     -- https://main.php.net/note/delete/130416/useless
Del: bad code    -- https://main.php.net/note/delete/130416/bad+code
Del: spam        -- https://main.php.net/note/delete/130416/spam
Del: non-english -- https://main.php.net/note/delete/130416/non-english
Del: in docs     -- https://main.php.net/note/delete/130416/in+docs
Del: other reasons-- https://main.php.net/note/delete/130416
Reject      -- https://main.php.net/note/reject/130416
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